• ALGAE
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• 제20권1호
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• pp.61-67
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• 2005

Agar was extracted from Gelidium amansii, which was harvested at the shores of Jeju Island in South Korea. As a unique solvent, the ability of dimethyl sulfoxide (DMSO) was used to separate agarose from agar by removing agaropectine and quality of the resultant agarose was characterized for chromatography purposes. Agar sample was agitated by motor-driven stirrer with DMSO in a water bath (at 70$^{\circ}C$ for 2 h) and centrifuged (3,000 rpm for 20 min). Resultant upper agarose layer was gelled, washed, dried and milled. The quality of agarose was evaluated by the analysis of proximate chemical composition, sulfate content, gelling strength and DNA migration. In this study, the separated agarose showed low sulfate amount (0.28%) and showed high gel strength (1190 g ${\cdot}\;cm^{-2}$). The resolution power and the ligase activities gave clear picture about the suitability of the present agarose for practical purposes.

• 대한기계학회논문집
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• 제15권5호
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• pp.1572-1586
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• 1991

본 연구에서는 볼 엔드밀 공구를 사용한 코너가공에서 절삭력을 예측하고, 가 공중 공구의 회전주기에 대한 최대 수평합력(max. resulant force)을 일정하게 유지시 키는 모델을 개발하고, 코너가공에 적용한다. 또 금형가공에는 절삭시간을 많이 소 요하여 생산성이 떨어지게 하는 주요한 원인이 되기 때문에 최대 수평합력을 황삭가공 에 적합하도록 설정하면 본 연구의 결과로 이송속도를 결정할 수 있다.

• 한국CDE학회논문집
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• 제4권1호
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• pp.32-42
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• 1999

Approximate lofting or skinning is one of practical surface modeling techniques well used in CAD and reverse engineering applications. Presented in this paper is a method for approximately lofting a given set of curves wihin a specified tolereance. It is based on refitting input curves simultaneously on a common knot vector and interpolating them to get a resultant NURBS surface. A concept of reducing the number of interior knots of the common knot vector is well adopted to acquire more compact representation for the resultant surface. Energy minimization is newly introduced in curve refitting process to stabilize the solution of the fitting problem and get more fair curve. The proposed approximate lofting provides more smooth surface models and realizes more efficient data reduction expecially when the parameterization and compatibility of input curves are not good enough. The method has been successfully implemented in a new CAD/CAM product VX Vision? of Varimetrix Corporation.

• Computational Structural Engineering : An International Journal
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• 제1권1호
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• pp.49-57
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• 2001

This paper presents exact solutions for the modal stress-resultant distributions for vibrating rectangular Mindlin plates involving two opposite sides simply supported while the other two sides free. These exact stress-resultants of vibrating plates with free edges, hitherto unavailable, are very important because they serve as benchmark solutions for checking numerical solutions and methods. Using the exact solutions of a square plate, this paper highlights the problem of determining accurate stress-resultants, especially the transverse shear forces and twisting moments in thin plates, when employing the widely used numerical methods such as the Ritz method and the finite element method. Thus, this study shows that there is a need for researchers to develop refinements to the Ritz method and the finite element method for determining very accurate stress-resultants in vibrating plates with free edges.

• 약학회지
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• 제36권1호
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• pp.12-16
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• 1992

A new method for the synthesis of alminoprofen, which is a non-steroidal antiinflammatory agent, was described. Ethyl 2-phenyl-propionate(4) was prepared by Friedel-Crafts reaction of benzene with ethyl ${\alpha}-chloro-{\alpha}(methylthio)acetate(1)$, followed by methylation and desulfurization of the resultant ethyl 2-(methylthio)phenylacetate(2). Ethyl 2-(p-aminophenyl)propionate(6) was obtained by nitration of (4) and successive reduction of ethyl 2-(p-nitrophenyl)propionate(5). Alminoprofen was synthesized by reaction of (6) with methallyl chloride, followed by hydrolysis of the resultant ethyl 2-(p-methylallylaminophenyl)propionate (7).

• 한국염색가공학회지
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• 제15권2호
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• pp.76-85
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• 2003

In this study, a continuous stabilization process is used to make high-performance carbon fiber from polyacrylonitrile(PAM)-based fibers. The effect of oxygen content of PAN-based fiber on the stabilization process and the properties of the resultant carbon fibers is investigated. In order to research the progress of stabilization reaction FT-IR, elemental analysis, density, DSC, etc are used. Stabilization is carried out in air atmosphere from the 200 to $300^\circ{C}$ temperature range. An increase of PAN-based fibers diameter reduces the oxygen content during the continuous stabilization process. A higher oxygen content increase the density, tensile strength and modulus in the resultant carbon fibers. The most appropriate oxygen content in the stabilized fiber should be about 12%. Fibers having more than 2% oxygen content yield carbon fibers with inferior properties. Those carbon fibers also have sufficient commercial availability.

• 한국정밀공학회지
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• 제13권4호
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• pp.87-96
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• 1996

On face milling operation a newly optimal tool, which can minimize the resultant cutting forces resulted from the cutting force model, was designed and manufactrued. Cutting experiments using the new and conventional tools were carried out and the cutting forces resulted from those tools were analyzed in time and frequency domains. The performance of the optimized cutter was tested through the dynamic cutting forces resulted form the newly designed tool are much reduced in comparision with those from the conventional tool. By reducing the dynamic cutting force fluctuations, machine tool vibrations can be reduced, and stable cutting operation can be carried out.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.30-37
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• 1999

The effects of heat treatment on the dimensional stability and bending properties of radiata pine sapwood were investigated. The dimensional stability was almost achieved by heat treatment though the loss of strength was accompanied as a negative effect. The improvement in dimensional stability of wood and the resultant reduction in bending properties were closely related to treatment temperature and duration. The optimum treatment conditions, which could be used to achieve a desired improvement in dimensional stability with resultant losses in modulus of rupture were proposed based on the results obtained in this study.

• 한국세라믹학회지
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• 제34권1호
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• pp.1-6
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• 1997

가정용 전자 렌지를 사용하여, SiO2-Al 분말 성형체로 이루어진 시편을 질화분위기에서 점화시켰다. 연소파대가 전파되면서 미반응물없이 Si와 AIN와 Al2O3를 석출하였으며, 냉각과정을 거치지 않고 곧바로 석출물들이 마이크로파를 흡수하여 고온에서 가열되어서 사이알론상을 합성하였다. 전자렌지안에서 SiO2-Al 분말성형체로부터 사이알론상들의 합성율은 일반적인 로내에서의 합성율보다 높았고, 공정시간이 불과 1시간내외에 이어서 에너지와 제조경비를 절약할 수 있었다.

• 한국주거학회논문집
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• 제7권2호
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• pp.121-129
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• 1996

This study was to estimate how about various effects on the body thermal sensation as air velocity. clo. mean radiant temperature and resultant temperature are varied. The indoor thermal environment elements are measured under the five different of air velocity. Using the above considerations. the following results are obtained. ▶ The states, the air velocity under 0.5 m/s and 0.63 to 0.9 clo. were shown that the comfort zone of mean radiant temperature by 21.2~24.7C, the neutral point by 22.8C, the resultant temperature by 20.7-24.4C and the neutral point by 22.6C. ▶ On equal condition, the draft was occurred at a given air-velocity under 0.5m.s. It was also appeared the floor panel heating system affecting the body thermal sensation by the subject’s below-chest parts and the local discomfort by sensations on the feet and the knees.